Chalcedony: Mentioned only in
(Revelation 21:19) as one of the precious stones in the
foundation of the New Jerusalem. The name of this stone is derived
from Chalcedon, where it is said to have been first discovered. In
modern mineralogy this is the name of an agate-like quartz of a
bluish colour. Pliny so names the Indian ruby. The mineral intended
in Revelation is probably the Hebrew nophekh, translated "emerald"
(Exodus 28:18; 39:11; Ezekiel 27:16; 28:13) It is rendered "anthrax" in the LXX.,
and "carbunculus" in the Vulgate.